scholarly journals Modelling the population dynamics of annual ryegrass (Lolium rigidum) under various weed management systems

2004 ◽  
Vol 23 (8) ◽  
pp. 723-729 ◽  
Author(s):  
J.L. Gonzalez-Andujar ◽  
C. Fernandez-Quintanilla
Weed Science ◽  
2009 ◽  
Vol 57 (4) ◽  
pp. 417-426 ◽  
Author(s):  
Vince M. Davis ◽  
Kevin D. Gibson ◽  
Thomas T. Bauman ◽  
Stephen C. Weller ◽  
William G. Johnson

Horseweed is an increasingly common and problematic weed in no-till soybean production in the eastern cornbelt due to the frequent occurrence of biotypes resistant to glyphosate. The objective of this study was to determine the influence of crop rotation, winter wheat cover crops (WWCC), residual non-glyphosate herbicides, and preplant application timing on the population dynamics of glyphosate-resistant (GR) horseweed and crop yield. A field study was conducted from 2003 to 2007 in a no-till field located at a site that contained a moderate infestation of GR horseweed (approximately 1 plant m−2). The experiment was a split-plot design with crop rotation (soybean–corn or soybean–soybean) as main plots and management systems as subplots. Management systems were evaluated by quantifying in-field horseweed plant density, seedbank density, and crop yield. Horseweed densities were collected at the time of postemergence applications, 1 mo after postemergence (MAP) applications, and at the time of crop harvest or 4 MAP. Viable seedbank densities were also evaluated from soil samples collected in the fall following seed rain. Soybean–corn crop rotation reduced in-field and seedbank horseweed densities vs. continuous soybean in the third and fourth yr of this experiment. Preplant herbicides applied in the spring were more effective at reducing horseweed plant densities than when applied in the previous fall. Spring-applied, residual herbicide systems were the most effective at reducing season-long in-field horseweed densities and protecting crop yields since the growth habit of horseweed in this region is primarily as a summer annual. Management systems also influenced the GR and glyphosate-susceptible (GS) biotype population structure after 4 yr of management. The most dramatic shift was from the initial GR : GS ratio of 3 : 1 to a ratio of 1 : 6 after 4 yr of residual preplant herbicide use followed by non-glyphosate postemergence herbicides.


2019 ◽  
Vol 70 (2) ◽  
pp. 140 ◽  
Author(s):  
Gulshan Mahajan ◽  
Kerry McKenzie ◽  
Bhagirath S. Chauhan

Annual ryegrass (ARG) (Lolium rigidum Gaudin) is a problematic weed for chickpea (Cicer arietinum L.) production in Australia. Understanding the critical period of control of ARG in chickpea is important for developing effective integrated management strategies to prevent unacceptable yield loss. Experiments were conducted over 2 years at the research farm of the University of Queensland, Gatton, to evaluate the effect of chickpea row spacing (25 and 75cm) and cultivar (PBA Seamer and PBA HatTrick) and ARG infestation period (from 0, 3 and 6 weeks after planting (WAP), and weed-free) on ARG suppression and grain yield of chickpea. Year×treatment interactions were not significant for any parameter, and none of the treatment combinations showed any interaction for grain yield. Average grain yield was greater (20%) with 25-cm than 75-cm rows. On average, PBA Seamer had 9% higher yield than PBA HatTrick. Average grain yield was lowest in season-long weedy plots (562kg ha–1) and highest in weed-free plots (1849kg ha–1). Grain yield losses were lower when ARG emerged at 3 WAP (1679kg ha–1). Late-emerged ARG (3 and 6 WAP) had lower biomass (4.7–22.2g m–2) and number of spikes (5–24m–2) than ARG that emerged early; at 0 WAP, weed biomass was 282–337g m–2 and number of spikes 89–120m–2. Compared with wide row spacing, narrow row spacing suppressed ARG biomass by 16% and 52% and reduced number of spikes of ARG by 26% and 48% at 0 WAP and 3 WAP, respectively. PBA Seamer suppressed ARG growth more effectively than PBA HatTrick, but only in the season-long weedy plots. Our results imply that in ARG-infested fields, grain yield of chickpea can be increased by exploring narrow row spacing and weed-competitive cultivars. These cultural tools could be useful for developing integrated weed management tactics in chickpea in combination with pre-emergent herbicides.


Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 508-516 ◽  
Author(s):  
Vince M. Davis ◽  
Kevin D. Gibson ◽  
Thomas T. Bauman ◽  
Stephen C. Weller ◽  
William G. Johnson

Horseweed is an increasingly problematic weed in soybean because of the frequent occurrence of glyphosate-resistant (GR) biotypes. The objective of this study was to determine the influence of crop rotation, winter wheat cover crops (WWCC), residual nonglyphosate herbicides, and preplant herbicide application timing on the population dynamics of GR horseweed and crop yield. A field study was conducted at a site with a moderate infestation of GR horseweed (approximately 1 plant m−2) with crop rotation (soybean–corn or soybean–soybean) as main plots and management systems as subplots. Management systems were evaluated by quantifying horseweed plant density, seedbank density, and crop yield. Crop rotation did not influence in-field horseweed or seedbank densities at any data census timing. Preplant herbicides applied in the spring were more effective at reducing horseweed plant densities than when applied in the previous fall. Spring-applied, residual herbicide systems were the most effective at reducing season long horseweed densities and protecting crop yield because horseweed in this region behaves primarily as a summer annual weed. Horseweed seedbank densities declined rapidly in the soil by an average of 76% for all systems over the first 10 mo before new seed rain. Despite rapid decline in total seedbank density, seed for GR biotypes remained in the seedbank for at least 2 yr. Therefore, to reduce the presence of GR horseweed biotypes in a local no-till weed flora, integrated weed management (IWM) systems should be developed to reduce total horseweed populations based on the knowledge that seed for GR biotypes are as persistent in the seed bank as glyphosate-sensitive (GS) biotypes.


2021 ◽  
Author(s):  
Martina Badano Perez ◽  
Hugh J Beckie ◽  
Gregory R Cawthray ◽  
Danica E Goggin ◽  
Roberto Busi

AbstractOverreliance on herbicides for weed control is conducive to the evolution of herbicide resistance. Annual ryegrass (Lolium rigidum Gaud.) is a species that is prone to evolve resistance to a wide range of herbicide modes of action. Rapid detection of herbicide-resistant weed populations in the field can aid farmers to optimize the use of herbicides for their control. The feasibility of a portable agar-based test to rapidly and reliably detect annual ryegrass resistance to key herbicides such as clethodim, glyphosate, pyroxasulfone and trifluralin on-farm was investigated. The three research phases of this study show that: a) easy-to-interpret results are obtained with non-dormant seed from well-characterised susceptible and resistant populations, and resistance is detected as effectively as with traditional dose-response pot-based resistance assays. However, the test may not be suitable for portable use on-farm because of b) the low stability of some herbicides such as trifluralin and clethodim in agar and c) the tendency of seed dormancy in freshly-harvested seeds to confound the results. The agar-based test is best used as a research tool as a complement to confirm results obtained in traditional pot-based resistance screenings. Comprehensive agar test and / or whole-plant resistance tests by herbicide application at the recommended label rate (whole plants grown in pots) are the current benchmark for proactive in- and off-season resistance testing and should be promoted more widely to allow early detection of resistance, optimization of herbicide technology use and deploy appropriate weed management interventions.


Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1505
Author(s):  
Ali Ahsan Bajwa ◽  
Sajid Latif ◽  
Catherine Borger ◽  
Nadeem Iqbal ◽  
Md Asaduzzaman ◽  
...  

Annual ryegrass (Lolium rigidum Gaud.), traditionally utilised as a pasture species, has become the most problematic and difficult-to-control weed across grain production regions in Australia. Annual ryegrass has been favoured by the adoption of conservation tillage systems due to its genetic diversity, prolific seed production, widespread dispersal, flexible germination requirements and competitive growth habit. The widespread evolution of herbicide resistance in annual ryegrass has made its management within these systems extremely difficult. The negative impacts of this weed on grain production systems result in annual revenue losses exceeding $93 million (AUD) for Australian grain growers. No single method of management provides effective and enduring control hence the need of integrated weed management programs is widely accepted and practiced in Australian cropping. Although annual ryegrass is an extensively researched weed, a comprehensive review of the biology and management of this weed in conservation cropping systems has not been conducted. This review presents an up-to-date account of knowledge on the biology, ecology and management of annual ryegrass in an Australian context. This comprehensive account provides pragmatic information for further research and suitable management of annual ryegrass.


2000 ◽  
Vol 51 (7) ◽  
pp. 937 ◽  
Author(s):  
H. Wu ◽  
J. Pratley ◽  
D. Lemerle ◽  
T. Haig

Allelopathy has been receiving world-wide attention for its potential in integrated weed management. A newly developed screening bioassay, the ‘equal-compartment-agar method’ (ECAM), was used to evaluate seedling allelopathy against annual ryegrass in a collection of 453 wheat accessions originating from 50 countries. Significant differences in allelopathic potential were found in this worldwide collection, inhibiting root growth of ryegrass from 9.7% to 90.9%. Wheat seedling allelopathy also varied significantly with accessions from different countries. Wheat allelopathic activity was normally distributed within the collection, indicating the involvement of multiple genes conferring the allelopathic trait. Of the 453 wheat accessions screened, 2 distinct groups were identified. Condor-derivatives were more allelopathic than Pavon-derivatives, with an average inhibition of root growth of ryegrass by 76% and 46%, respectively. Research was further extended to investigate the near isogenic lines derived from Hartog (Pavon-derivative) and Janz (Condor-derivative). Hartog and its backcrossed lines were less allelopathic than Janz and its backcrossed lines, inhibiting root length of ryegrass by 45% and 81%, respectively. These results strongly indicate that wheat allelopathic activity might also be controlled by major genes, depending on the particular populations. The present study demonstrates that there is a considerable genetic variation of allelopathic activity in wheat germplasm. It is possible to breed for cultivars with enhanced allelopathic activity for weed suppression.


Weed Science ◽  
1997 ◽  
Vol 45 (1) ◽  
pp. 166-171 ◽  
Author(s):  
W. Carroll Johnson ◽  
B. G. Mullinix

Studies were conducted from 1990 through 1994 near Tifton, GA, on the population dynamics of yellow nutsedge and certain annual weeds in peanut—corn and peanut—cotton rotations. Converse rotation sequences were included to eliminate year effects. Continuous fallow plots (noncrop) were included for comparison. Within each crop, including fallow, were 3 levels of weed management: low, moderate, and intensive. Weed densities and numbers of yellow nutsedge tubers were not affected by crop rotations, but they were affected by individual crops and weed management systems in each crop. Fallow plots, including those with intensive fallow weed management using tillage and nonselective herbicides, consistently contained more yellow nutsedge plants and tubers than other plots. Moderate and intensive weed control systems in peanut and cotton reduced yellow nutsedge densities and tubers, but only peanut yields were increased by intensive weed management. Weed management systems did not affect yellow nutsedge densities in corn, although yields were increased by moderate and intensive systems due to improved control of other weeds. Our results suggest that uninterrupted plantings of peanut, corn, or cotton with moderate levels of weed management are generally sufficient to suppress yellow nutsedge and allow for optimum crop yield. If fields are fallow, yellow nutsedge population densities and tubers will increase exponentially, even with intensive fallow weed management.


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